Maister's season was ended three weeks ago by a shoulder injury that required surgery and he told his teammates of his decision on Tuesday morning.
The 28-year-old played 23 games for West Coast between 2008 and 2010 and, after being delisted by the Eagles, revived his career in the WAFL in 2011.
He earned a second chance with the Saints, playing 21 games for the club in three seasons.
His 2013 season was ruined by wrist and hamstring injuries and he spent the majority of 2014 in the VFL.
"It is with real disappointment that we say goodbye to Beau as he has become one of the most admired and respected players within our group," head of football Chris Pelchen said.
"Since joining the Saints, he has performed to his absolute ability through sheer hard work and determination … qualities that have endeared him to everyone at the club.
"We thank Beau for his commitment to the Saints and wish him every success for the future."
Maister will pursue business interests in Western Australia.